Thanks. Need to dive in a bit better, but I did clarify some things in my mind which bear mentioning.
1. Sourcing JDBC data is not a streaming operation, but a batching one. Which makes sense, since you generally slurp rather than stream relational data, so within the constraints provided you’ll be operating on whole result sets. 2. Kafka is useful for mating batch processes (like slurping a database) with stream ones (reading out the results of a database query then distributed to various processing nodes). Prez Cannady p: 617 500 3378 e: revp...@opencorrelate.org <mailto:revp...@opencorrelate.org> GH: https://github.com/opencorrelate <https://github.com/opencorrelate> LI: https://www.linkedin.com/in/revprez <https://www.linkedin.com/in/revprez> > On Mar 9, 2016, at 6:46 AM, Prez Cannady <revp...@correlatesystems.com> wrote: > > I suspected as much (the tuple size limitation). Creating my own InputFormat > seems to be the best solution, but before i go down that rabbit hole I wanted > to see at least a semi-trivial working example of JDBCInputFormat with Scala > 2.11. > > I’d appreciate a look at that prototype if its publicly available (even if it > is Java). I might glean a hint from it. > > Prez Cannady > p: 617 500 3378 > e: revp...@opencorrelate.org <mailto:revp...@opencorrelate.org> > GH: https://github.com/opencorrelate <https://github.com/opencorrelate> > LI: https://www.linkedin.com/in/revprez <https://www.linkedin.com/in/revprez> > > >> On Mar 9, 2016, at 3:25 AM, Chesnay Schepler <ches...@apache.org >> <mailto:ches...@apache.org>> wrote: >> >> you can always create your own InputFormat, but there is no >> AbstractJDBCInputFormat if that's what you were looking for. >> >> When you say arbitrary tuple size, do you mean a) a size greater than 25, or >> b) tuples of different sizes? >> If a) unless you are fine with using nested tuples you won't get around the >> tuple size limitation. Since the user has to be aware of the nesting (since >> the fields can be accessed directly via tuple.f0 etc), this can't really be >> done in a general-purpose fashion. >> If b) this will straight-up not work with tuples. >> >> You could use POJO's though. then you could also group by column names. >> >> I'm not sure about Scala, but in the Java Stream API you can pass the >> InputFormat and the TypeInformation into createInput. >> >> I've recently did a prototype where the input type is determined >> automatically by querying the database. If this is a problem for you feel >> free to ping me. >> >> On 09.03.2016 03:17, Prez Cannady wrote: >>> I’m attempting to create a stream using JDBCInputFormat. Objective is to >>> convert each record into a tuple and then serialize for input into a Kafka >>> topic. Here’s what I have so far. >>> >>> ``` >>> val env = StreamExecutionEnvironment.getExecutionEnvironment >>> >>> val inputFormat = JDBCInputFormat.buildJDBCInputFormat() >>> .setDrivername("org.postgresql.Driver") >>> .setDBUrl("jdbc:postgresql:test") >>> .setQuery("select name from persons") >>> .finish() >>> >>> val stream : DataStream[Tuple1[String]] = env.createInput(...) >>> ``` >>> >>> I think this is essentially what I want to do. It would be nice if I could >>> return tuples of arbitrary length, but reading the code suggests I have to >>> commit to a defined arity. So I have some questions. >>> >>> 1. Is there a better way to read from a database (i.e., defining my own >>> `InputFormat` using Slick)? >>> 2. To get the above example working, what should I supply to `createInput`? >>> >>> >>> Prez Cannady >>> p: 617 500 3378 >>> e: <mailto:revp...@opencorrelate.org>revp...@opencorrelate.org >>> <mailto:revp...@opencorrelate.org> >>> GH: <https://github.com/opencorrelate>https://github.com/opencorrelate >>> <https://github.com/opencorrelate> >>> LI: >>> <https://www.linkedin.com/in/revprez>https://www.linkedin.com/in/revprez >>> <https://www.linkedin.com/in/revprez> >>> >>> >>> >>> >>> >>> >>> >>> >>> >> >
